Macular thickness and macular volume measurements using spectral domain optical coherence tomography in normal Nepalese eyes

Abstract

PurposeTo record the normative values for macular thickness and macular volume in normal Nepalese eyes.MethodsIn all, 126 eyes of 63 emmetropic subjects (mean age: 21.17±6.76 years; range: 10–37 years) were assessed for macular thickness and macular volume, using spectral domain-optical coherence tomography over 6×6 mm2 in the posterior pole. A fast macular thickness protocol was employed. Statistics such as the mean, median, standard deviation, percentiles, and range were used, while a P-value was set at 0.05 to test significance.ResultsAverage macular thickness and total macular volume were larger in males compared to females. With each year of increasing age, these variables decreased by 0.556 μm and 0.0156 mm3 for average macular thickness and total macular volume, respectively. The macular thickness was greatest in the inner superior section and lowest at the center of the fovea. The volume was greatest in the outer nasal section and thinnest in the fovea. The central subfield thickness (r=−0.243, P=0.055) and foveal volume (r=0.216, P=0.09) did not correlate with age.ConclusionMales and females differ significantly with regard to macular thickness and macular volume measurements. Reports by other studies that the increase in axial length reduced thickness and volume, were negated by this study which found a positive correlation among axial length, thickness, and volume.

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“…16 Tan et al 28 evaluated a Chinese population and found a CST value of 322.2±98.2 μm, which is much higher than the normal mean values measured with the Spectralis SD-OCT (270.2±22.5 μm). Grover et al 11 also found a greater CST in Asian individuals using the Spectralis SD-OCT. Pokharel et al 19 found a CST of 247.7±19.9 μm in an Indian population, which is lower than the normal values established for the Spectralis SD-OCT; they also reported that the superior quadrant was thicker, which is similar to our results. However, racial diversity may not always correspond to the actual variation in the retinal macular thickness needed for a normative OCT database, which would be better evaluated through environmental, socioeconomic, and geographic variations in the study population.…”

“…7,9 Significant differences in the macular central subfield thickness (CST) have been reported in healthy subjects among different races, genders, and age groups; many differences were also found between several scan protocols and OCT units. 6,8,[10][11][12][13][14][15][16][17][18][19][20] Normative macular thickness values using different OCT units on a specific population are needed to identify reference values for many eye conditions. A normative database for macular thickness helps us determine if a patient falls within or outside normal values for his age and race; in a clinical research setting, this database would help us determine a patient's inclusion or exclusion criteria, additionally, if the treatment is meant to decrease macular thickness, we need to be sure that we have an abnormally thick retina at the beginning in order to adequately measure its variations.…”

Intraocular inflammatory cytokines in patients with neovascular age-related macular degeneration before and after initiation of intravitreal injection of anti-VEGF inhibitor

“…For measurement of retinal thickness, a traditional Early Treatment Diabetic Retinopathy Study (ETDRS) grid containing three concentric rings 1, 3, and 6 mm in diameter was employed 20 . The mean retinal thicknesses of the macula in the central 1, 3 and 6 mm on the ETDRS grid were defined as CMT ≤ 1 mm, CMT ≤ 3 mm, and CMT ≤ 6 mm, respectively 21 . During the study period of 8 weeks, follow-up examinations were performed before the first IVA and after the third IVA.…”

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“…Total macular volume in healthy eyes is reported to be around 8.5 mm 3 . 34 We observed a TVOL of approximately 9 mm 3 in DME patients undergoing intravitreal treatment after two years, which might suggest residual cystoid fluid within the macular area even after long-term treatment. So far, real-life data on aflibercept treatment in eyes with DME is rare.…”